[WebAPKRestore] Move web_app_url_loader to components/webapps/browser

so it can be shared by Android for restoring webapps.

Bug: 41496289
Change-Id: Ia43ec81edebac08e89d44c60e6d4ea0b84ee75a6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5402330


Reviewed-by: Glenn Hartmann <hartmanng@chromium.org>
Reviewed-by: Hidehiko Abe <hidehiko@chromium.org>
Reviewed-by: Adam Rice <ricea@chromium.org>
Reviewed-by: Daniel Murphy <dmurph@chromium.org>
Commit-Queue: Ella Ge <eirage@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1282369}